The Stone Messenger

I have been intrigued with historical cairns like this one for years. These are large rock cylinders, carefully constructed, far from any modern trail or route. I have noticed them along the Missouri River Breaks of eastern Montana, but this is the first significant one I have found in western Montana's Madison River Valley.
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The best explanation I have found is that cairns like these were established by early sheepherders and may have been built to indicate distance and direction to watering holes. Some cairns date back further, being built by Native Americans.